61 Dodge Lancer 6 to ? conversion

My slant in my 64 Dart Wagon used to get 25mpg average. That was with a 1bbl and point ignition. I would suggest to just put a slant back in it with a electronic ignition upgrade. And hardened valve seats for unleaded. The only way to not good gas mileage is to not keep the valves in adjustment, and points and plugs. Other than that that's it. As far as longevity goes I had over 500,000 miles on my motor before it died. Even then it really didn't die, I lost a valve due to the seats being beat up from not running leaded fuel. I could of pulled the head and had it rebuilt but it was an excuse to go with a v8. I also believe the newer V6 will have a fitment issue due to a small engine compartment just like the V8. And being that the early cars never had the V6 getting a special exhaust manifold to fit like the V8 is not gonna happen. I would also suggest telling your customer about another website. www.slantsix.org